This invention is concerned with the cephalosporin antibiotics. In particular it is concerned with a process for the preparation of deacetoxycephalosporanic acids, 3-methyl-7-acylamino-3-cephem-4-carboxylic acids.
Heretofore the 3-methyl-3-cephem ring system of the deacetoxycephalosporanic acids has been elaborated via a penicillin sulfoxide rearrangement as described by U.S. Pat. No. 3,275,626 and by the acylation of 7-aminodeacetoxycephaloxporanic acid, 7-ADCA.
The prior art is replete with descriptions of 3-thiosubstituted methyl-3-cephem compounds commonly prepared by the nucleophilic displacement reaction of a cephalosporanic acid with a sulfur nucleophile.
For example the compounds described by U.S. Pat. Nos. 3,239,515, 3,239,516, 3,446,803, 3,516,997, 3,243,435, 3,258,461 and 3,261,832 are representative of such 3-thiosubstituted methyl-3-cephem cephalosporins.
It is an object of this invention to provide a process for the preparation of deacetoxycephalosporanic acids. In particular it is an object of this invention to provide a process for the preparation of deacetoxycephalosporanic acids which employs as starting materials the readily available 3-thio substituted methyl-2-cephem compounds of the prior art.